Apparatus for the production of combustible gases from solid carbonaceous materials



Dec. 28, 1965 -r. E. BAN

APPARATUS FOR THE PRODUCTION OF COMBUSTIBLE GASES FROM SOLIDCARBONACEOUS MATERIALS 2 Sheets-Sheet 1 Filed Jan. 2, 1962 @505 4 M Qe503 oz u k m H W A W T N K I\ 1 m m g I I @508 w fi P m umyzju H 4 0112 w. T v a M $9.5 5. 2 y 3! VS 22 E Q WV fir 2o $88K 23 7. Sm 28 \.l jg Q umES 9% ma NEE/5 .H |.lI 081 m 8 2mm 8% Y wmwwaww wv( 3 69 v 7 @50363% Na 01 23 4 M. NW2; No 2E6 9 520. Q md u NwUDOOUQ.

Dec. 28, 1965 'r. E. BAN

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United States Patent 3,226,212 APPARATUS FOR THE PRODUCTION OF COM-BUSTIBLE GASES FROM SOLID CARBONA- CEOUS MATERIALS Thomas E. Ban,Cleveland Heights, Ohio, assignor, by

mesne assignments, to McDowell-Wellman Engineering Company Filed Jan. 2,1962, Ser. No. 163,502 2 Claims. (Cl. 48-63) This invention relates asindicated to an improved apparatus for the production of combustiblegases from solid carbonaceous materials, such as coal, and moreparticularly to a continuous system for the production of producer gasor coal gas from such solid carbonaceous fuels.

The production of producer gas or water gas, coal gas, and coke formetallurgical purposes is an art which has been practiced for manyyears. It has now been found that greatly increased efiiciency can beachieved in the production of such products by causing the interactionof gases and solids by supporting a bed of solids on a continuouslymoving conveyor including a plurality of pallets and grates, anddirecting gases through the voids of the solid particles. The followingsubject matter relates to methods and apparatus for gasifying coal andcarbonizing coal or other such solid carbonaceous fuels on such anapparatus, and with a special reference to the well known Dwight-Lloyd"machine. Gasification of such solid carbonaceous materials as coal asdescribed herein refers to the conversion of the combustible matter to auseful gas. Carbonization of coal or other such solid carbonaceousmaterial as described herein refers to the removal and collection of thevolatile matter while converting the residual solids into a pyrolyticchar, or coke. This invention will be illustrated with primary referenceto the use of coal as the fuel burden, but it is to be understood thatthe apparatus and processes of the present invention may be applied tosynthetic compositions similar to coal such as briquettes comprised ofcarbon and tar residues, or green (unhardened) pellets composed ofground coal and water.

It is the principal object of the present invention, therefore, toprovide a system for the conducting of solid-gas reactions wherein thesolid is a solid carbonaceous fuel material.

Other objects of the invention will appear as the description proceeds.

This invention may be better understood by reference to the annexeddrawings which are to be understood as being illustrative of a preferredembodiment of the present invention without limiting the invention tothe precise scope thereof, and wherein:

FIG. 1 is a diagrammatic and schematic illustration of one form ofapparatus for forming producer gas from coal.

FIG. 2 is a diagrammatic and schematic illustration of one form ofapparatus useful in the production of coal gas and coke in accordancewith the present invention.

Briefly stated, the present invention is in the provision of a systemfor forming a gas including carbon monoxide, hydrogen and methane from asolid carbonaceous fuel. Ignition means are provided including aplurality of pallets mounted on an elongated horizontally disposedendless conveyor, which pallets have a plurality of spaced grate barsdefining the bottom thereof and through which gases may be passed. Thesepellets are adapted to contain a fuel evenly distributed thereon to formwhat is termed a fuel burden. The fuel burden is ignited, and means areprovided for passing a gas through the fuel burden for the purpose ofentraining and extracting therefrom normally liquid components of thefuel. Depending upon the nature of the gas which is passed through thefuel burden, either producer gas or coal gas will be produced, and thesolid by-product of the reaction will be coal ash or coke. The apparatusalso includes means for isolating the liquid components from the gassuch as a scrubbing tower or condenser, and means for recovering thegas. In a preferred embodiment of the invention, the solid-gas reactionis conducted in a field chamber, and thus the entire endlessconveyorpallet system is enclosed.

Gasification of coal may be represented by two principal reactions asfollows:

(1) C+O 2CO (exothermic) (2) C+H O CO+H (endothermic) The heat ofreaction (1) is utilized to sustain the reaction (2) to produce watergas. Air, steam and coal are generally used to make producer gas whichresults from the simultaneous conduct of both reactions. Water gasresults from sequential carrying out of the two reactions abovementioned. Instead of air, oxygen may be used along with the water asthe gaseous consituents of the reaction, and coal, coke, charcoal, orother carbon containing materials can be used as the solid phase orsolid reactant.

When air and steam are reacted with bituminous coal, a producer gas ofthe following composition is generally formed:

Percent Carbon monoxide 25 Hydrogen 10 Methane 3 Illuminants 1 Carbondioxide 3 Nitrogen 58 Ash, clinker and tar are the usual solid andliquid byproducts of the gas producer. An approximate material balancefor an apparatus of the type herein contemplated shows the followingreactants and products per pound of coal:

Reactants: Pounds Air 4 Water 0.2

Coal 1.0

Products:

Producer gas 5 Ash 0.2

Tar 0.1

Producer gas is usually used for combustion purposes because it hasfavorable flame characteristics. It is also used to make synthesis gasand the carbon monoxide and hydrogen is used for making chemicals suchas wood alcohol and ammonia, respectively.

A simplified system for making producer gas in a chambered system withDwight-Lloyd machine of conventional design is illustrated in FIG. 1.The chambered system prevents undesirable, unfiltered drafts fromentering the system inadvertently. It is hazardous to allow air into thewindboxes containing producer gas because of the possibility of creatingan explosive mixture. Thus there is shown in FIG. 1 a sealed chamberenclosing an endless conveyor 10 having a plurality of pallets 11thereon. The bottoms of the pallets are formed from a plurality of gratebars spaced apart approximately This provides sufiicient permeabilityfor the gases, and sufiicient solid structure to support the fuelburden. Solid carbonaceous fuel, such as coal, is stored in a storagebin 12 fitted with a mechanical feeder 13 which is adapted to regulatethe rate of feed co-operatively with the rate of speed of the conveyor10. Suitable means such as a hopper 14 are provided to distribute solidcarbonaceous fuel on the pallets to a substantial uniform depth as theconveyor is moved past the outlet thereof. The fuel burden or coal bedas shown in FIG. 1 immediately passes under a gas burner 15 where thefuel burden is ignited. Hood 16 which may be a single hood or aplurality of individual hood units substantially covers the conveyorway, and may in desirable instances be sealed through the employment ofsliding seals with the pallets to prevent the escape of gases therefrom.

On the underside of the conveyor belt and fuel burden, there is provideda wind box 17 which under the influence of gas pump or fan 18 providesthe region of reduced pressure beneath the fuel burden, and hence thedownward flow of gas therethrough. Gases from the windbox 17 areconducted by means of conduit 19 to a scrubbing tower 20 of conventionaldesign to effect removal of liquid constitutents from the gas. Theseconstituents normally include tar and other liquid hydrocarbon andphenolic fractions. The effluent from this scrubber may be conducted toany suitable storage means, not shown. It is desirable to recycle asmall portion of the gas through a side arm 22 by means of a pump 23.This provides a positive pressure within the sealed chamber whichprevents leakage of air through joints provided for admission of variouscomponents of the apparatus.

By the time the fuel burden reaches the right hand end of the conveyor10 shown in FIG. 1 it has been reduced to ash. This material iscollected in a bin 25 which may be provided with a crushing device 26 tobreak up clinker to such sizes as may be handled by the exit feedervalve 27. The numerical values given in FIG. 1 show a balance ofmaterials in a specific example.

Referring now more particularly to FIG. 2, similar parts have been givenidentical numbers. Instead of air mixed with steam or water beingintroduced to the hood as indicated in FIG. 1, coal gas produced inaccordance with the reaction is recycled through conduit 30 to the hood16. A portion of the gas is bled off to storage through exit pipe 31.Instead of ash and clinker being removed at the end of the conveyor beltas shown in FIG. 1, charcoal or coke is produced and is recovered as auseful product in accordance with FIG. 2. The chambered apparatus ofFIG. 2 can be used for carbonizing coal by recycling coal gas through aheated coal bed. By heating one ton of coal in the absence of air, thefollowing products can be formed:

Pounds Coke or char 1200 Coal gas 400 Tars and hydrocarbon liquids 400In accordance with FIG. 2, coal is fed to the pressurized coal systemand uniformly layered on the conveyor pallets through the hopper 14, asabove indicated. An ignition burner 15 supplies heat to the top layersof coal. As

'this layer feeds under the hood, recycled coal gas forces the hot zonedownward. The heated zone causes the expulsion of gas, hydrocarbonliquids and tars from the coal, and the medium is conducted through ascrubber for removing the liquid fractions. Char or coke is removed fromthe discharge end of the conveyor and from the chamber by means of astar-gate feeder. Coal gas is a relatively inert medium for transferringheat in decomposing coal. This gas has a general composition as follows:

The coal gas recycle system allows a sufficient quantity of gas in thesystem for transferring heat. The recycled gas may be heatedadditionally either directly or indirectly if more heat is desired toretain the normally liquid components of the gas in a vaporized statefor removal from the sealed chamber system.

There has thus been provided an improved system for solid-gas reactionswherein the solid is a carbonaceous material such as coal and thereactant gas is a moist air or coal gas material. By continuouslysupplying the coal or other solid carbonaceous material to ahorizontally disposed elongated conveyor bed having a plurality ofpallets thereon, and in a predetermined quantity, a solid-gas phasereaction may be made to occur with the production of useful products.The coal is ignited, and thereafter the reactant gases introduced forthe purpose of removing from the coal volatile components thereof andundergoing reaction therewith for the production of useful productseither solid products, liquid products or gaseous products. Thesereactions are carried out in a sealed chamber, and means are suppliedexternally of the chamber for separating the products of the reaction totheir several useful components.

Other modes of applying the principle of this invention may be employedinstead of those specifically set forth above, changes being made asregards the details herein disclosed provided the elements set forth inany of the following claims, or the equivalent of such be employed.

It is, therefore, particularly pointed out and distinctly claimed as theinvention:

1. A system for forming and recovering a coal gas rich in hydrogen andmethane, and residual carbonaceous solids from granular coal whichcomprises:

(a) a plurality of aligned pallets mounted on an elongated horizontallydisposed endless conveyor,

(b) means at one extremity of said conveyor for distributing saidgranular coal to a substantially uniform depth to form a coal burden onsaid pallets,

(c) means, above said coal burden on said pallets and adjacent to saidmeans for distributing, for igniting said fuel burden,

((1) separate means including a hood in juxtaposed relation to saidaligned pallets for supplying recycle coal gas to said ignited coalburden, and means for supplying air in combination with steam to said ignited fuel burden,

(e) sealed chamber means for enclosing said ignition means, saidconveyor and said hood and isolating them from the ambient atmosphere,

(f) means for passing said coal gas down through said fuel burden onsaid conveyor, to extract volatiles from said coal and yielding a coalgas rich in hydrogen and methane, and to entrain normally liquidcomponents derived from said coal,

(g) means below said conveyor for isolating said liquid components fromsaid coal gas,

(h) means connected to said means (g) for recovering said liquiddepleted coal gas,

(i) means connected to said means (h) for recycling a portion of saidliquid depleted coal gas to said hood, and

(j) means for recovering residual solids from the other extremity ofsaid conveyor.

2. A system for forming and recovering a gas rich in carbon monoxide,and hydrogen, and residual solids from a solid granular carbonaceousfuel which comprises:

(a) a plurality of aligned pallets mounted on an elongated horizontallydisposed endless conveyor;

(b) means at one extremity of said conveyor for distributing saidgranular fuel to substantially uniform depth to form a fuel burden onsaid pallets;

(0) means, above said fuel burden on said pallets and adjacent to saidmeans for distributing, for igniting said fuel burden;

(d) separate means including a hood in juxtaposed relation to saidaligned pallets on said conveyor and including means for supplying airin combination with steam to said ignited fuel burden;

(e) means for passing said steam containing gas down through said fuelburden on said conveyor to effect a water gas reaction therewith andyield a producer gas rich in carbon monoxide and hydrogen, and toentrain normally liquid components derived from said fuel;

(f) separate means below said conveyor for isolating said liquidcomponents from said producer gas;

(g) means connected to said separate means (if) for recovering saidliquid depleted producer gas;

(i) sealed chamber means for enclosing said ignition means, conveyor andhood and isolating them from the ambient atmosphere.

References Cited by the Examiner UNITED STATES PATENTS MORRIS O. WOLK,Primary Examiner.

(h) means for recovering residual solids from the other 15 MAURICEBRINDISI, Examiner'- extremity of said conveyor; and

2. A SYSTEM FOR FORMING AND RECOVERING A GAS RICH IN CARBON MONOXIDE,AND HYDROGEN, AND RESIDUAL SOLIDS FROM A SOLID GRANULAR CARBONACEOUSFUEL WHICH COMPRISES: (A) A PLURALITY OF ALIGNED PALLETS MOUNTED ON ANELONGATED HORIZONTALLY DISPOSED ENDLESS CONVEYOR; (B) MEANS AT ONEEXTREMITY OF SAID CONVEYOR FOR DISTRIBUTING SAID GRANULAR FUEL TOSUBSTANTIALLY UNIFORM DEPTH TO FORM A FUEL BURDEN ON SAID PALLETS; (C)MEANS, ABOVE SAID FUEL BURDEN ON SAID PALLETS AND ADJACENT TO SAID MEANSFOR DISTRIBUTING, FOR IGNITING SAID FUEL BURDEN; (D) SEPARATE MEANSINCLUDING A HOOD IN JUXTAPOSED RELATION TO SAID ALIGNED PALLETS ON SAIDCONVEYOR AND INCLUDING MEANS FOR SUPPLYING AIR IN COMBINATION WITH STEAMTO SAID IGNITED FUEL BURDEN;